Field of the Invention
The present invention relates to a swing arm structure for a saddle riding type vehicle.
Description of Related Art
A configuration is known, as disclosed in Japanese Patent Laid-Open No. 2009-248875, for a swing arm structure for a saddle riding type vehicle that includes a vehicle body frame and a swing arm supported swingably in a vertical direction on the vehicle body frame. The vehicle body frame disclosed in Japanese Patent Laid-Open No. 2009-248875 includes center frame portions spaced away from each other in a vehicle width direction and an intermediate frame portion. The configuration includes a swing arm having a front end portion disposed between the center frame portions and the intermediate frame portion in the vehicle width direction, and a pivot shaft that is passed through the center frame portions, the front end portion of the swing arm, and the intermediate frame portion to extend in the vehicle width direction.
The swing arm structure further includes a nut that threadedly engages, under a condition in which the swing arm front end portion is disposed between the center frame portions and the intermediate frame portion in the vehicle width direction, an end portion of the pivot shaft that is passed through the entire width direction of the foregoing vehicle body frame elements. The swing arm structure thereby tightens the vehicle body frame (the center frame portions and the intermediate frame portion). This particular structure requires that the vehicle body frame have strength to withstand the tightening. As a result, the vehicle body frame is required to have a thicker wall and the structure additionally needs a large-sized cross member. This hampers effort to promote reduction in size and weight of the swing arm structure.